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  <title>Document</title>
</head>
<body>
  <input type="checkbox" checked>
  <input type="radio" checked>
  <select>
    <option value="">北京</option>
    <option value="">上海</option>
    <option value="">广州</option>
    <option value="" selected>邯郸</option>
    <option value="">石家庄</option>
  </select>

  <script>
    var ck = document.querySelector('input[type=checkbox]');
    console.log(ck.checked);
    ck.checked = false;
  </script>
</body>
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